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In water electrolysis experiments on hydrogen production, boiling effectively decreases the overpotential of the oxygen evolution reaction (OER) [Li et al. Int. J. Hydrog. Energy. 2022, 47(61):25499–510]. This study constructed a theoretical model to quantitatively explore the mechanism by which boiling reduces the OER overpotential. The model considers dissolved oxygen, liquid water, gaseous oxygen, and water vapor flowing through the porous transfer layer (PTL). The results showed that boiling increases the molar flux of gaseous oxygen and reduces the dissolved oxygen concentration. The PTL embedded in the catalyst layer (CL) increased the mass transfer resistance of dissolved oxygen and increased the dissolved oxygen concentration in the CL. Once boiling is superimposed on the OER, it attracts more dissolved oxygen to the water vapor bubbles and significantly decreases the dissolved oxygen concentration at the CL, thereby reducing the Nernst loss of the OER. • A dimensionless OER model with boiling is developed. • The model quantitatively clarifies the OER characteristics at boiling. • Boiling decreases dissolved oxygen concentration at the CL. • Current contribution ratio for the OER under bubbles rises at boiling. [ABSTRACT FROM AUTHOR]

Liquid hydrogen has attracted widespread attention due to industrial decarbonization as an excellent carrier of renewable energy accommodation. Accurate prediction of the heat transfer coefficient during flow boiling has become a fundamental prerequisite for enhancing the design rationality and safety of hydrogen devices since a slight heat leak will trigger flow boiling. A novel selection standard of the dataset for liquid hydrogen flow boiling is proposed, and an experimental database of liquid hydrogen is compiled, including 923 data points from 5 sources. The prediction performance of eight conventional empirical correlations and six machine learning models for liquid hydrogen flow boiling is compared and evaluated. Results show that the prediction ability of machine learning models for the heat transfer coefficient of liquid hydrogen flow boiling is much higher than that of traditional correlations. Fang correlation is recommended to use as the calculation benchmark due to simplicity and reliability if the inlet condition is obscure. The Extra tree model shows the most excellent evaluating performance among the six machine learning models with a mean absolute deviation of 11.44% and a fairly superior R 2 of 0.9543. The Froude number Fr exhibits an essential impact according to the feature importance analysis, which may need to be taken into account when developing new empirical correlations. An improved correlation for the flow boiling of liquid hydrogen is provided based on the Fang correlation, achieving a mean absolute deviation of 18.61% and a mean relative deviation of 16.49%. The results of this paper can offer some theoretical guidance for the design of a liquid hydrogen apparatus. [Display omitted] • A novel selection standard of data set for liquid hydrogen flow boiling is proposed. • Fang correlation is recommended as the calculation benchmark due to simplicity and reliability. • Extra tree model has the best prediction performance with MAD of 11.44% and R 2 of 0.9543. • Froude number Fr exhibits an essential impact on heat transfer. • An improved correlation is proposed with MAD of 18.61% and MRD of 16.49%. [ABSTRACT FROM AUTHOR]

The pressure drop characteristics of subcooled water were experimentally investigated in a circular cooling channel with and without a twisted tape (TT) under high heat fluxes, which was designed for the water-cooling structure of the divertor target in a tokamak device. The working medium was deionized water, and the main parameters were mass flux G = 3000–8000 kg·m−2·s−1, inlet pressure of the test section p = 3, 4.2, 5 MPa, equivalent one-side heating flux qe = 5~10 MW·m−2. The off-center circular channel is electrically heated to simulate the unilateral radiation heating on the divertor target by high-temperature plasma. The pressure drop experiment of vertical upward circular cooling channels under high and unilateral heat flux is carried out. The influences of the TT and system parameters such as qe, G, and p on the pressure drop of the test section (Δp) were discussed in detail. In the single-phase (SP) flow region, Δp is mainly affected by the TT, G, and qe. The pressure drop with a TT is significantly higher than that without a TT, a higher G and a lower qe lead to a greater Δp. In the subcooled boiling (SB) flow region, Δp is correlated with the TT, qe, G, and p: the influence of the TT and G decreases, while the influence of p increases. The higher the qe, the higher the G, and the lower the p, the larger the Δp. The results show that almost all of the SP pressure drop correlations for heated circular channels overestimate the experimental pressure drop coefficient ratio for a given viscosity ratio. According to the test results, a new correlation of SP pressure drop under high and unilateral heat fluxes has been proposed, the average error (AE) and root mean square error (RMSE) of which are 0.26% and 3.17%, respectively. [ABSTRACT FROM AUTHOR]

The issue of maintaining low-gradient combustion in the conditions of high heat extraction has been investigated numerically in this work. The analyses include the application of a convective boundary condition at the wall (with estimated boiling heat transfer coefficient); analysis of the Internal Recirculation Device's impact on combustion products and heat transfer under low-gradient conditions; and comparison of both traditional and low-gradient combustion modes. It was shown that the Internal Recirculation Device material and geometry has a significant impact on the nitrogen oxide (NO x ) formation mechanism, as NO 2 emission becomes predominant and can rise up to several hundreds ppm. What is more, along with decrease in thermal resistance of the IRD, CO emissions also increase rapidly, even achieving over 2000 ppm. Additionally, the convective heat transfer rate decreased by about 25% after switching from traditional to low-gradient combustion, whereas the radiative mechanism increased by ≈40% compared to traditional mode. It should also be mentioned that the low-gradient combustion applied in this work achieved approximately 10% higher efficiency than conventional combustion. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the changes occurring as a result of boiling (100°C, 1 h) small brown snail (Cornu aspersum aspersum) meat in relation to its proximate composition, calcium, phosphorus and cholesterol content, as well as the profile of fatty acids and nutritional quality indices of the lipids. This species of snail was selected for research because it is currently of the greatest economic importance among edible terrestrial snails. It was hypothesized that the cooking effect may be different for foot and visceral sac. Samples for the research were collected from 6 populations bred on experimental fields of the National Research Institute of Animal Production in balice (Poland). The foot and the visceral sac, the edible parts of the snail species under investigation, were analysed separately, raw and boiled in water. The results were then compared to analogous studies carried out by other authors on beef, pork and poultry. It was found that in the visceral sac of Cornu aspersum aspersum the shares of dry matter, crude protein, fat, ash, calcium and phosphorus were greater than those in the foot (P<0.05), both in the raw and boiled material, whereas the cholesterol content was higher in the foot (P<0.05). Generally, especially in the foot, the heat treatment elevated the levels of the afore-mentioned quantities, yet the increases were not always statistically significant. Boiling the snail meat caused moderate changes in the fatty acid composition. The profile of the fatty acids and the nutritional quality indices of the foot fat were more advantageous than those in the visceral sac. In both parts of the snail carcass, the polyunsaturated fatty acids/saturated fatty acids (PUFA/SFA) ratio substantially exceeded the minimum value of 0.45 recommended by the British Department of Health. However, the n-6/n-3 ratio was too high, exceeding the maximum recommended level of 4.0 twofold and as much as threefold in the case of the foot and the visceral sac, respectively. In the foot, due to boiling, an increase of the share of sfa and monounsaturated fatty acids (MUFA) was observed, while PUFA, n-6 and n-3 decreased. In the visceral sac, the changes were less pronounced with a slight decrease of the share of sfa and PUFA, and an increase of MUFA. Therefore, in the foot, boiling worsened the PUFA/SFA ratio, the nutritive value index (NVI = (C18:0 + C18:1) / C16:0) and dietary fatty acids having a desirable neutral and hypocholesterolemic effect in humans (DFA = Σ MUFA + Σ PUFA + C18:0), but in the visceral sac these indices practically did not change. On the whole, the trends of the changes in terms of chemical composition due to boiling found in the small brown snail meat are similar to those after heat treatment of meat from popular farm animals, but the ranges of the changes differ. [ABSTRACT FROM AUTHOR]

Francisco Gomes de Amorim (1827-1891), a Portuguese writer who emigrated to Amazonia in 1837, he lived several experiences that were later reported on his literary production and in the various contributions he made to periodicals, as well as in correspondence exchanges with his contemporaries. According to a compilation carried out by Costa Carvalho (2000), and in files available in Póvoa de Varzim, we can affirm that Gomes de Amorim had a broad vision on the themes he favored. Acording to a possible perspective for the 19th century, the author brought to light discussions that were boiling at that time, such as the social inequalities he experienced in Amazonia and the experience of Portuguese emigration to Brazil. [ABSTRACT FROM AUTHOR]

An experimental study of nucleate pool boiling is conducted on the GNP/Ni-Al2O3 (GNP-graphene nano particle) nano-composite coated copper surfaces at atmospheric pressure using distilled water (DI) as boiling fluid. The microporous coated surfaces are fabricated using hybrid method (electrochemical deposition of GNP and nano-composite coating of Ni-Al2O3). A modified surface structure is generated as a result of this deposition, and different surface morphological parameters of this modified structure, such as surface structure, roughness and wettability, are investigated. Results show the enhancement in boiling heat transfer coefficient (BHTC) and critical heat flux (CHF) in nano-composite coated surfaces compared to the bare Cu surface. The improvement in boiling performance is mostly attributable to the enhancement of roughness and wettability as well as the higher thermal conductivity of the GNP/Ni-Al2O3 nano-coating. The highest CHF of 2217 (kW/m2) and BHTC of 112.83 (kW/m2K) is found in case of composite nano-coated superhydrophilic (CNCS) surfaces, which are 104% and 123% more than the bare Cu surface. High-speed visualization is used to conduct a quantitative investigation of the dynamics of bubble, including active bubble site density, emission frequency of the bubble, bubble departure diameter and their impact on the performance of pool boiling heat transfer. [ABSTRACT FROM AUTHOR]

Hierarchical surfaces comprised both microscale and nanoscale structures have been previously studied as a means of targeting multiple length scales to achieve superior pool boiling performance. However, preceding studies have focused almost exclusively on high surface tension working fluids, while technologically important low surface tension fluids have remained largely unexplored. Due to their significantly lower surface tension these liquids tend to push out the air trapped in surface cavities of the heating surface, resulting in fewer nucleation sites compared to the same surface in water at low to moderate superheats. Thus, developing effective surface modification techniques for pool boiling in dielectric liquids and understanding the multiphase physics behind them is a pressing need in order to overcome these performance limitations and accelerate their adoption. In this work, we utilize scalable manufacturing techniques to realize four separate surface types (planar, nanoscale-modified, microscale-modified, and hierarchical) and experimentally determine their respective pool boiling performance within the low surface tension commercial working fluid HFE-7100. A maximum heat transfer enhancement of 125% at 38 K of superheat was observed for the best performing samples, which interestingly were nanoscale-modified and not those of the hierarchical type. Visual observations via high-speed video analysis of vapor bubble behavior are utilized to explain the underlying multiphase physics as to why these samples performed so well and future directions for achieving surface optimization across multiple length scales. [ABSTRACT FROM AUTHOR]

It is very important to accurately analyze the heat transfer characteristics of a working fluid in the cooling system based on subcooled flow boiling. In contrast to previous computational fluid dynamics (CFD) studies for the subcooled flow boiling of water or synthetic refrigerants in a vertical tube, we study the subcooled flow boiling characteristics of CO2 in a horizontal tube at -30 ℃. Our model is built based on Eulerian multi-phase model combined with the interfacial area concentration and wall heat flux partitioning models, and it is solved by the CFD solver, ANSYS FLUENT 19.3. This paper determines a reasonable bubble waiting time coefficient (CWT), critical Weber number (Wecri), and turbulence model (TM) for modelling of flow boiling heat transfer of CO2 by combining with uniform design (UD), Taguchi method, multiple quadratic regression (MQR) model and grid search method. As the result, the reasonable values of CWT and Wecri, and reasonable TM were determined as CWT = 0.8, Wecri = 0.7, and RNG k–ε model. This work has a significant contribution to study the subcooled flow boiling heat transfer characteristics of CO2 at low temperature. The proposed approach could be actively applied to improve the solution accuracy of the heat transfer of a working fluid in various heat transfer system. [ABSTRACT FROM AUTHOR]

Peatlands are globally important stores of soil carbon (C) formed over millennial timescales but are at risk of destabilization by human and climate disturbance. Pools are ubiquitous features of many peatlands and can contain very high concentrations of C mobilized in dissolved and particulate organic form and as the greenhouses gases carbon dioxide (CO2) and methane (CH4). The radiocarbon content (14C) of these aquatic C forms tells us whether pool C is generated by contemporary primary production or from destabilized C released from deep peat layers where it was previously stored for millennia. We present novel 14C and stable C (δ13C) isotope data from 97 aquatic samples across six peatland pool locations in the United Kingdom with a focus on dissolved and particulate organic C and dissolved CO2. Our observations cover two distinct pool types: natural peatland pools and those formed by ditch blocking efforts to rewet peatlands (restoration pools). The pools were dominated by contemporary C, with the majority of C (~50%–75%) in all forms being younger than 300 years old. Both pool types readily transform and decompose organic C in the water column and emit CO2 to the atmosphere, though mixing with the atmosphere and subsequent CO2 emissions was more evident in natural pools. Our results show little evidence of destabilization of deep, old C in natural or restoration pools, despite the presence of substantial millennial‐aged C in the surrounding peat. One possible exception is CH4 ebullition (bubbling), with our observations showing that millennial‐aged C can be emitted from peatland pools via this pathway. Our results suggest that restoration pools formed by ditch blocking are effective at preventing the release of deep, old C from rewetted peatlands via aquatic export. [ABSTRACT FROM AUTHOR]

The maximum temperature limit at which liquid boils explosively is referred to as the superheat limit of liquid. Through various experimental studies on the superheating limit of liquids, rapid evaporation of liquids has been observed at the superheating limit. This study explored the water nucleation process at the superheat limit achieved in micro-platinum wires using a molecular interaction model. According to the molecular interaction model, the nucleation rate and time delay at 576.2 K are approximately 2.1 × 1011/(μm3μs) and 5.7 ns, respectively. With an evaporation rate (116.0 m/s) much faster than that of hydrocarbons (14.0 m/s), these readings show that explosive boiling or rapid phase transition from liquid to vapor can occur at the superheat limit of water. Subsequent bubble growth after bubble nucleation was also considered. [ABSTRACT FROM AUTHOR]

The response surface methodology was used to optimize the hydrothermal treatment conditions of foxtail millet using the soak-boil or soak-steam method. The optimized hydrothermal treatment conditions for soak-boil method were, soaking time of 2 h at 50.5 °C and boiling time of 6.2 min, which resulted in a decortication yield of 82.91%, TPC (45.19 mg GAE/100 g), TAA (55.62%), peak viscosity (270 cP), trough viscosity (264 cP) and final viscosity (440 cP). In the case of soak-steam method, the optimized conditions were, soaking time of 2.05 h at 44 °C followed by steaming at 110 °C for 5 min, which resulted in the decortication yield of 86.89%, TPC (48.64 mg GAE/100 g), TAA (69.42%), peak viscosity (165 cP), trough viscosity (207cP) and final viscosity (297 cP). Both the hydrothermal treatments significantly increased decortication yield, TPC and TFC contents of decorticated millet kernel, however, lowered the pasting viscosities. The drying kinetics studies of optimized samples of both the treatments were performed at 40, 45 and 50 °C. The soak-steamed grain had shown lower effective diffusivity coefficient (Deff), whereas the soak boil millet samples had indicated lower activation energy (Ea). For soak-boil and soak-steam optimized samples, the highest values of R2 (0.99949 and 0.0051), the lowest chi-square (χ2) (3.24 × 10−5 and 0.99879) and lowest RMSE (0.0105 and 0.0001) respectively, were obtained for the Midilli model. While comparing the experimental and predicted values, a good agreement between the experimental and predicted values of moisture ratio with drying time curve confirms the suitability of Midilli model in describing drying behaviour of hydrothermally treated foxtail millet. [ABSTRACT FROM AUTHOR]

The mechanistic model LAKE2.3 was tested for its capability to predict of methane (CH4) emissions from reservoirs. Estimates of CH4 emissions from the Mozhaysk reservoir (Moscow region) provided by the model showed good agreement with instrumental in situ observations for several parameters of the water ecosystem. The average CH4 flux calculated by the model is 37.7 mgC-CH4 m−2 day−1, while according to observations, it is 34.4 mgC-CH4 m−2 day−1. Ebullition makes the largest contribution to the emissions from reservoirs (up to 95%) due to low methane solubility in water and the high oxidation rate of diffusive methane flux. During the heating period, an increase in methane emission is observed both in the model and empirical data, with a maximum before the onset of the autumn overturn. An effective parameter for calibrating the diffusive methane flux in the model is the potential rate of methane oxidation. For ebullition flux, it is the parameter q10 (an empirical parameter determining the relationship between methane generation and temperature) because methane production in bottom sediments is the most important. The results of this research can be used to develop mechanistic models and provide a necessary step toward regional and global simulations of lacustrine methane emission using LAKE2.3. [ABSTRACT FROM AUTHOR]

Dissolved oxygen plays a central role for all organisms dwelling in water. However, the flux of oxygen by ebullition has not received much attention in environmental science. For a better quantitative understanding of the oxygen flux due to ebullition, we conducted a series of laboratory experiments, where we forced macrophytes to produce photosynthetic gas bubbles. Raising the CO2 concentration in the water greatly increased bubble formation. Depth was varied to compare the results with theoretically predicted composition of photosynthetic bubbles forming at minimum required gas pressure. Oxygen concentrations lay between this theoretical line as lower boundary (ca. 21% O2 at 0.3 m depth and 45% of O2 at 4.5 m) and 45% of oxygen as the purely empirical upper limit for all depths. As a consequence, no bubble formation was observed at depths below 4.5 m. Plain Language Summary: Under light, green plants produce oxygen, when they grow. Submerged plants can produce bubbles under these conditions. Some of these bubbles rise to the surface and hence transport oxygen out of the water into the atmosphere. We studied this process by measuring the composition of such bubbles in a laboratory experiment. Adding carbonic acid to the water boosted the bubble production a lot. Depending of depth, there is a minimum of gases required for bubble formation, which yields a theoretical minimum concentration for oxygen. In all experiments, the oxygen concentration of bubbles was above atmospheric percentage of 21%, but always below 45%. Key Points: Photosynthetic gas bubbles from submerged macrophytes contain other gases beyond oxygenThe depth‐dependent lower limit can be derived from minimum gas pressure consideration for the formation of bubblesEmpirically we find an upper limit of 45% of oxygen in the collected gas bubbles [ABSTRACT FROM AUTHOR]

This study investigated the effect of single-boiling crystallization of high-yielding sugarcane on sugar and molasses production on a factory-plant scale compared with triple-boiling crystallization of conventional sugarcane. The sugar extraction at the roll-milling process was similar between high-yielding sugarcane KY01-2044 with high fiber and conventional sugarcane NiF8. The weight of sugar yield per sugarcane decreased by 32.6 % compared with the conventional system, whereas the yield of molasses and bagasse increased by 143.1 % and 11.5 %, respectively. The results indicated that sugar, molasses, and bagasse-derived electricity could increase simultaneously when the yields of high-yielding sugarcane were higher by a factor of 1.5 than conventional levels. Furthermore, A-molasses obtained by a single-boiling crystallization had less coloration and better fermentability and operability than conventional C-molasses. In conclusion, this study showed that combining high-yielding sugarcane and single-boiling crystallization could increase sugar production and generate high-quality molasses suitable for biofuel and bagassederived electricity production. [ABSTRACT FROM AUTHOR]

Shallow lakes and ponds undergo frequent temporary thermal stratification. How this affects greenhouse gas (GHG) emissions is moot, with both increased and reduced GHG emissions hypothesised. Here, weekly estimations of GHG emissions, over the growing season from May to September, were combined with temperature and oxygen profiles of an 11 ha temperate shallow lake to investigate how thermal stratification shapes GHG emissions. There were three main stratification periods with profound anoxia occurring in the bottom waters upon isolation from the atmosphere. Average diffusive emissions of methane (CH 4) and nitrous oxide (N 2 O) were larger and more variable in the stratified phase, whereas carbon dioxide (CO 2) was on average lower, though these differences were not statistically significant. In contrast, there was a significant order of magnitude increase in CH 4 ebullition in the stratified phase. Furthermore, at the end of the period of stratification, there was a large efflux of CH 4 and CO 2 as the lake mixed. Two relatively isolated turnover events were estimated to have released the majority of the CH 4 emitted between May and September. These results demonstrate how stratification patterns can shape GHG emissions and highlight the role of turnover emissions and the need for high-frequency measurements of GHG emissions, which are required to accurately characterise emissions, particularly from temporarily stratifying lakes. [ABSTRACT FROM AUTHOR]

To study the pressure drop characteristics of hypervapotron, which was designed as a water-cooling structure in the divertor dome of the fusion reactor, the pressure drop tests of subcooled water were carried out in a vertically upward hypervapotron. To simulate the one-side radiant heating condition in the engineering application, the non-uniform heat fluxes were obtained by using the off-center electrically heating method. The system parameters were as follows: mass flux G = 2000–5000 kg·m−2·s−1, inlet pressure p = 2–4 MPa, and equivalent one-side radiating heat flux qe = 0–5 MW·m−2. The effects of the parameters on the pressure drop were discussed in detail. It was observed that in the single-phase (SP) region, the pressure drop was little influenced by the inlet fluid temperature (Tb,in). However, in the subcooled boiling region, the pressure drop increased rapidly with the increasing Tb,in. A higher G leads to a high pressure drop. In the SP region, the influence of p on the pressure drop is not obvious, and the pressure drop decreased with the increasing qe. The test data are used to evaluate the typical pressure drop correlation, and the results show that none of these correlations can predict the pressure drop well under the test conditions. Therefore, a new pressure drop correlation is proposed for subcooled water in a hypervapotron under high and non-uniform heat fluxes. The new correlation has a high prediction accuracy for the test data, and the mean relative error (MRE) and root mean square error (RMSE) are 0.72% and 4.33%, respectively. The test results have a reference value for the design of the water-cooling structure of the diverter. [ABSTRACT FROM AUTHOR]

In current study, a flow boiling experimental examination has been performed on water, water-TiO2 nanofluid, and water-Al2O3 nanofluid and Gradient Boost Regression model was established to predict the Nusselt number of TiO2 and Al2O3 nanofluids. Nusselt number was calculated by varying heat flux, Reynolds number, and volumetric concentration. Good agreement was shown by water results acquired from experiments with the correlation of Chen and CFD. Results demonstrated that the Nusselt number of TiO2 and Al2O3 nanofluid was larger than water. Increment in Nusselt number was noticed with the increment in concentration, heat flux, and Reynolds number. It was seen that Al2O3 nanofluid was superior to TiO2 nanofluid. Highest improvement in the Nusselt number was 37% shown by Al2O3 nanofluid when compared to water. Correlations of Nusselt number were developed for both nanofluids. GBR-GSO machine learning model showed a good agreement with the experimental Nusselt number. [ABSTRACT FROM AUTHOR]

Refractories play an important role in societies' progress as they enable extensively consumed materials to be processed such as steel and cement. Because of the high demand of these supplies, refractory-lined equipment comprises massive structures that have large dimensions and weighs several tons. Conversely, laboratory samples, used to study the behavior of these materials, are orders of magnitude smaller and often found weighing less than 1 kg. Within the context of refractory castable drying, this work aims to investigate the impact of size effects on water removal dynamics during thermogravimetry tests. The analysis of mass loss and its derivative with respect to temperature indicates that increasing the heating rate applied in the small samples can lead to a better reproduction of the evaporation and ebullition stages of the drying of large ones, due to the compensation effect of the faster temperature increase on the smaller sample sizes leading to similar thermal gradients. Furthermore, the presence of polymeric fibers and their influence on the size effect are also examined, showing that the increased permeability induced by such additives reduces the intensity of the scale effect. Additionally, it was found that for cubic samples with sizes equal to or larger than 10 cm, a kink in the temperature evolution measured at the center of the samples took place. A hypothesis based on the results and on observations of recent studies is proposed to explain this phenomenon, attributing it to the rapid evaporation of accumulated liquid water at those positions. This study also highlights the importance of considering the size-dependent nature of drying dynamics in refractory castables, as conventional thermogravimetry on laboratory scale samples may overlook important phenomena. Understanding the mechanisms occurring at real structural scales during water removal is crucial for predicting their behavior upon heating and enabling faster and safer drying processes for refractories. [ABSTRACT FROM AUTHOR]

As the unpredictable nature of the Earth's climate persists, the scholarly attention dedicated to climate research has undergone a notable transition, shifting its emphasis from the conventional notion of global warming to a greater disconcerting occurrence commonly referred to as "global boiling." The present article endeavors to elucidate the scientific evidence that posits a discernible alteration in climate patterns, specifically towards an exacerbation of extreme heat events. Furthermore, this study aims to delve into the various factors that are believed to be instrumental in precipitating this noteworthy phenomenon. Furthermore, we engage in a comprehensive examination of the potential ramifications on ecological systems, human communities, and the imperative necessity for proactive measures aimed at both mitigating and adapting to these challenges. This paper endeavors to elucidate the potential issues presented by the period of global boiling through a thorough examination of existing research and data. Furthermore, it seeks to underscore the significance of concerted efforts to effectively tackle this pressing matter. [ABSTRACT FROM AUTHOR]

Boiling is an efficient mode of heat transfer and has important applications that use high heat flux systems. However, a single wettable boiling surface is not appropriate for the dual requirements of low superheat for nucleation and high critical heat flux. Here, we present a hydrophilic composite and a functional hydrophilic-hydrophobic partitioned porous structure that significantly improves boiling heat transfer performance via a double-sintering process. The superheat requirement for the onset of nucleate boiling decreased from 2°C on the single hydrophilic porous structure to 1°C on the hydrophilic-hydrophobic porous structure, the critical heat flux was reduced by 3.3% in the early stages of boiling (below 250 kW/m2), the heat transfer efficiency increased by 20%, and the heat transfer was comparable to that of the hydrophilic porous structure. Bubble dynamics were observed using a high-speed camera. The results demonstrate that the bubble nucleation sites mainly occur in the hydrophobic region and this is attributed to a decrease in the energy barrier for nucleation. The bubble dynamic statistics revealed that the product of the diameter of the bubble and the bubble escape frequency are similar for composite surfaces and hydrophilic porous surfaces, which is consistent with Zuber's conclusion. The synergistic effect of the hydrophilic-hydrophobic partitioned porous structure can promote nucleation in the hydrophobic region and retain capillary suction for liquid reflux in the hydrophilic region to enhance boiling heat transfer. This work enables the large-scale deployment of heat exchanger surface processing technology because of its low cost, availability, and reliability. [ABSTRACT FROM AUTHOR]

In this paper, pool boiling of ethanol at atmospheric pressure was analyzed. The enhanced surfaces were made of copper, on which grooves with a depth ranging from 0.2 to 0.5 mm were milled in parallel. The widths of the microchannels and the distances between them were 0.2 mm, 0.3 mm and 0.4 mm, respectively. The highest heat transfer coefficient, 90.3 kW/m2K, was obtained for the surface with a microchannel depth of 0.5 mm and a width of 0.2 mm. The maximum heat flux was 1035 kW/m2. For the analyzed surfaces, the maximum heat flux increase of two and a half times was obtained, while the heat transfer coefficient increased three-fold in relation to the smooth surface. In the given range of heat flux 21.2–1035 kW/m2, the impact of geometric parameters on the heat transfer process was presented. The diameters of the departing bubbles were determined experimentally with the use of a high-speed camera. A simplified model was proposed to determine the diameter of the departure bubble for the studied surfaces. [ABSTRACT FROM AUTHOR]

Effects of various physical mechanisms at the stage of vapor bubble collapse and the subsequent formation of a shaped-charge jet in the process of laser-induced boiling near the end of a thin waveguide immersed in a cold liquid is studied numerically. Depending on the evaporation intensity, three process modes are identified and described. [ABSTRACT FROM AUTHOR]

• This paper presents R290 (propane) and R1270 (propylene) local boiling heat transfer coefficients inside a BPHE. • R1270 exhibits boiling heat transfer coefficients very similar in trend, and 5–10% higher in magnitude, than those of R290. • Nucleate boiling seems to be the governing heat transfer regime both in R290 and R1270 tests. • Longo et al. (2015) model exhibits the best predicting performance with a MAPE of 7.7% and 6.9% for R290 and R1270, respectively. • R290 and R1270 exhibit boiling heat transfer performance between those of R404A and those of R410A. This paper presents the local heat transfer coefficients of R290 (propane) and R1270 (propylene) boiling inside a Brazed Plate Heat Exchanger (BPHE). A new test section was designed for measuring the local heat transfer coefficient in refrigerant two-phase heat transfer in a BPHE. The test section includes two thick AISI316L stainless steel corrugated plates instrumented with 36 T-type thermocouples for measuring the local plate surface temperature, the local heat flux and the local heat transfer coefficient in 9 positions along the refrigerant channel. The experimental tests were carried out at a boiling temperature of 10 °C, in the refrigerant mass flux range 5 − 17.5 kg m −2 s−1 with an inlet vapour quality ranging from 0.24 to 0.37 and an outlet vapour quality around 1.00. The global uncertainty of the local heat transfer coefficient measurement is within ±12.7%, and ±15.6%, for R290, and R1270, respectively. Nucleate boiling seems to be the governing heat transfer regime both in R290 and R1270 tests. Consolidated correlations for nucleate boiling inside BPHE show a fair agreement with all the experimental data. R290 and R1270 exhibit boiling heat transfer performance between those of R404A and those of R410A. [ABSTRACT FROM AUTHOR]

Summary: In this study, the changes in bioactive properties, phenolic compound profile and mineral results of fresh, boiled and dried pea seeds were investigated. It was observed that the total phenol, flavonoid and antioxidant capacity results of heat‐treated peas were decreased when compared to the control. Total carotenoid result of peas dried in oven and microwave were significantly increased compared to control and boiled peas (P < 0.05). Oven or microwave heating treatments increased the L* values of samples, while boiling caused a decrease in L* results. As with the bioactive properties of peas, the phenolic component amounts of peas were also low in the dried samples, and a linear correlation was obtained between the phenolic components and bioactive properties of the treated pea seeds. The highest protein content was detected in the peas dried in the conventional heater. Both fresh and dried peas are rich in K, P, Ca, Mg, S, Fe and Zn. K results of fresh and dried pea samples ranged from 19 258.50 (boiling) to 23 820.31 ppm (dw; oven). [ABSTRACT FROM AUTHOR]

Objective and Methods: The reliable estimation of phase transition physicochemical properties such as boiling and melting points can be valuable when designing compounds with desired physicochemical properties. This study explores the role of external rotational symmetry in determining boiling and melting points of select organic compounds. Using experimental data from the literature, the entropies of boiling and fusion were obtained for 541 compounds. The statistical significance of external rotational symmetry number on entropies of phase change was determined by using multiple linear regression. In addition, a series of aliphatic hydrocarbons, polysubstituted benzenes, and di-substituted napthalenes are used as examples to demonstrate the role of external symmetry on transition temperature. Results: The results reveal that symmetry is not well correlated with boiling point but is statistically significant in melting point. Conclusion: The lack of correlation between the boiling point and the symmetry number reflects the fact that molecules have a high degree of rotational freedom in both the liquid and the vapor. On the other hand, the strong relationship between symmetry and melting point reflects the fact that molecules are rotationally restricted in the crystal but not in the liquid. Since the symmetry number is equal to the number of ways that the molecule can be properly oriented for incorporation into the crystal lattice, it is a significant determinant of the melting point. [ABSTRACT FROM AUTHOR]

In this study, deionized water pool boiling experiments were performed on austenitic stainless steel AISI 304 steel balls with different initial temperatures. The disturbance and rupture of the vapor film during the quenching process are obtained by a high-speed camera. The temperature profile of the steel ball center during cooling was obtained by thermocouple temperature measurement. Based on the inverse heat conduction method, the inverse heat transfer program was independently developed to solve the surface temperature of the steel ball, the interfacial heat transfer coefficient and the heat flux. The results show that there is no film boiling when the steel ball temperature is 650 °C. There are four stages of film boiling, transition boiling, nucleate boiling and natural convection when the steel ball temperature is between 700 and 1000 °C. The thickness of the vapor film increases with the increase of the initial quenching temperature. At an initial temperature of 1000 °C, the thickness of the vapor film in the equatorial direction is 3.5 to 3.6 mm. With the increase of the initial temperature, the duration and rupture time of the vapor film were prolonged, and the central and boundary LFP temperatures gradually decreased. When the initial temperature is between 700 ~ 1000 °C, the vapor film lasts about 6.5 ~ 32.1 s, and the LFP temperatures at the center are between 612.3 °C and 514.7 °C, respectively. When the initial temperature is 650 °C, the maximum IHTC value is about 11,700 W/(m2·℃), and the critical heat flux is 1545.85 kW/m2. As the initial temperature is 1000 °C, the maximum IHTC value is about 14,900 W/(m2·°C), and the critical heat flux is 1508.43 kW/m2. [ABSTRACT FROM AUTHOR]

Nanoparticle deposition in nanofluid boiling can significantly impact heat transfer efficiency. However, there is still much to be uncovered regarding the heterogeneity of micro-structures in nanoparticle deposition and how to quantitatively model variations in deposition layer thickness. To gain a deeper understanding, we conducted experiments where single boiling bubbles were grown from an artificial micro-cavity in SiO2 nanofluids with varying concentrations and durations under a constant heat flux. Our results reveal that the nanoparticle deposition region increases with concentration and boiling duration. Notably, while the deposition morphology is irregular near the bubble nucleation site, it becomes more uniform further away from the bubble nucleation site. We believe that the heterogeneity in the micro-structure of the deposition layer is due to differences in the evaporation time of the liquid microlayer at different positions, variations in its thickness beneath a single boiling bubble, and dependency of nanoparticles Brownian motion on temperature. Additionally, the thickness of the deposition layer decreases as the distance from the nucleation site increases. To accurately describe this variation in thickness, we have proposed a semi-empirical correlation based on the liquid microlayer evaporation theory and the conservation of mass of nanoparticles beneath a single boiling bubble. The thickness of the nanoparticle deposition layer is determined by the number of growing bubbles, liquid density, initial thickness of the liquid microlayer, local nanoparticle concentration, and local nanoparticle stacking density. This study provides valuable insights into optimizing micro-structures or thickness of the deposition layer, leading to improved nanofluid boiling heat transfer. [ABSTRACT FROM AUTHOR]

Bubble nucleation is the initial stage of flow boiling and plays an important role in boiling heat transfer. However, bubble nucleation occurs at a microscopic scale, rendering it challenging for the macroscopic computational fluid dynamics method to realistically simulate this intricate process. In this paper, based on the coupled volume-of-fluid and level set method, a heterogeneous nucleation model is improved and conducted to simulate the subcooled flow boiling in a rectangular mini-channel, considering these conditions both in the presence and absence of a microlayer. The coefficient of the original heterogeneous nucleation model is adjusted across a range from 0.1 to 10.0 times its previous value to establish multiple new nucleation models for illustrating their effects on flow patterns and heat transfer characteristics. For flow boiling without a microlayer, when the coefficient of the original heterogeneous nucleation model is halved, the nucleate boiling intensity upstream of the channel diminishes, resulting in a reduction in the heat transfer coefficient. Nevertheless, this alteration mitigates the formation of slug flow and the appearance of dry patches near the channel outlet, consequently averting a sharp increase in outlet wall superheat. Quantitatively, relative differences of 23.83% and 90.48% in average and local maximum wall superheat are observed, respectively. In contrast, the presence of a very thin microlayer beneath the growing and slipping bubble in flow boiling with a microlayer is notable. This microlayer quickly evaporates, dissipating more than 77% of the input heat flux and substantially expanding the bubble volume. Consequently, under identical wall superheat conditions, the influence of variations in the number of activated bubbles induced by different heterogeneous nucleation models on heat transfer and flow patterns in flow boiling is significantly attenuated. Specifically, when the difference in nucleus site density remains within a tenfold range, the differences in the average and maximum wall superheat are limited to just 16.78% and 33.86%, respectively. Concerning flow boiling in a mini-channel featuring a microlayer, the simulation results verify that large deviations in the activated bubble number have few effects on the flow pattern and wall superheat, greatly reducing heterogeneous nucleation model requirement and promoting the numerical study of flow boiling. [ABSTRACT FROM AUTHOR]

A model capable of predicting the thermodynamic state of the working fluid and its related properties inside a thermosyphon and a heat pipe is proposed. The model theoretically analyzes the entropy changes of various thermodynamic processes and determines the possible locations of the state points on a temperature-specific entropy (T-s) and a specific enthalpy-specific entropy (h-s) diagram at each stage of the thermodynamic cycle. The analysis reveals that the working fluid enters the condenser in a superheated state, while it enters the evaporator in a subcooled state, irrespective of the operating conditions. Analytical expressions are derived to predict the changes in the temperature, pressure, specific volume, entropy, and enthalpy during each thermodynamic process, along with expressions for estimating entropy generation. The effects of varying input heating power ( Q i n ̇ ), the fill ratio, the device aspect ratio, and the device inclination angle (θ) on the working fluid behavior are examined, revealing that they affect the thermodynamic state of the working fluid during operation. The conclusion drawn in the existing heat pipe literature that the operating parameters only influence the thermal resistance of thermosyphons and heat pipes is, therefore, incomplete. The geometric and the operational parameters influence the state of the working fluid at each stage of the thermodynamic cycle. The present thermodynamic model, in conjunction with existing heat pipe theory, completely describes thermosyphon and heat pipe operation under any given set of conditions. [ABSTRACT FROM AUTHOR]

This work reports the nucleate boiling heat transfer characteristics of n-pentane on smooth and enhanced surfaces. Surface modifications were carried out on stainless steel surfaces by fabricating microholes of diameter between 0.3 and 0.7 mm arrays using electric discharge machining. Pool boiling experiments were carried out at normal atmospheric pressure. Experiments have been performed for applied effective heat flux range between 1 and 10 W cm−2. An enhancement of 20–45% in heat transfer coefficient was observed on the enhanced surface compared to the smooth surface. The heat transfer improvement in the enhanced surface can be attributed to more active nucleation sites, better rewetting phenomenon, and favorable bubble growth and release mechanism. Further changing the material from steel to brass enhances the heat transfer coefficient by 20%. This will be a viable option as a cooling technology for high-power electronic industries. [ABSTRACT FROM AUTHOR]

The temperature rise characteristics of PMSM (permanent magnet synchronous motor) during operation were studied under the condition of BHT (boiling heat transfer) in cooling water. The subcooling boiling heat transfer model, RPI (Rensselaer polytechnic institute), was used to calculate and improve the computational accuracy of simulation results. The experiments have shown that, when the motor was tested and simulated after preheating, the temperature rise characteristics were similar to test data because the boiling heat transfer phenomenon of the motor was taken into account, with an error of 1.7%, which was more accurate than the error of 7.5% without boiling. Therefore, from the results obtained from the experiments, the phenomenon of boiling heat transfer in cooling system has a significant effect on the temperature rise characteristic of the motor, which should be regarded as an important factor. Due to the influence of two-phase flow boiling heat transfer, the temperature rise of the motor in the plain areas is 4–5 °C higher than that in the high altitude areas. Consequently, if the motor is operated in high altitude areas, its temperature rise characteristic has better effect compared with plain area. Additionally, when BHT in cooling water is considered, the temperature of the motor drops as the rate of flow increases. In the meantime, the temperature difference between the minimum flow rate and the maximum flow rate is about 1 °C, which means that the increase in rate of flow can enhance the boiling heat transfer effect. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive overview of research conducted on heat transfer and crisis phenomena during boiling. It discusses the main stages and trends in the development of this research over the past 60 years, highlighting the increase in studies due to advancements in experimental and theoretical methods and materials science. The article covers topics such as heat transfer coefficient, critical heat flux, nucleate boiling, and heat transfer crisis under forced flow conditions. It also emphasizes the importance of future studies on nanofluid boiling. The text presents various experimental studies on heat transfer during boiling, exploring the effects of coatings and surface structures on heat transfer efficiency. It also discusses phenomena such as vapor films, heat transfer crisis, and vapor explosions. The studies offer valuable insights for researchers and engineers in fields such as microelectronics, power electronics, and energy systems. [Extracted from the article]

Quenching plays an important role in the material processing. Water impingement jet quenching involves phenomena such as nucleate boiling, Leidenfrost effect, rewetting, etc. Stronger thermal gradients could induce cracks in the material. Thermal boundary conditions of the process depends on temperature, space, time, and material discontinuity. This study mainly focuses on the thermal modeling of moving water jet quenching of semi-solid hot vertical aluminum plate with latent heat release during the solidification by using Peridynamics (PD). The obtained thermal profile is compared with the infrared camera's thermal field data to identify the boiling curve parameters on the cracked plate. The PD model with the incorporation of cracking dynamics is giving agreeable results with the experimental thermal field. Modeling quenching heat transfer using PD will enhance the coupling of hot tear origination and propagation simulation, which is quite challenging with other numerical methods. The application of PD in quenching heat transfer with phase change is the first of its kind. The advantages and limitations of the peridynamic approach for this problem is critically evaluated and the simulated results are compared with the experimental measurement of temperature profiles. [ABSTRACT FROM AUTHOR]

Reservoir operation policies affect sediment methane (CH4) production and pathways through complex influence on hydrodynamic and biogeochemical processes in reservoir water and sediment. However, the underlying influencing mechanisms, especially the impact of operations on sediment CH4 production and pathways, remain poorly understood. This study combines a physical‐biogeochemical model with a reservoir operation model to evaluate operation impacts on spatiotemporal sediment CH4 production and release dynamics and to analyze affiliated processes and driving factors. Three typical operation policies (i.e., standard, hedging, eco‐friendly) are selected to create the operation scenarios, and a coupled physical‐biogeochemical model is adopted to simulate and compare sediment CH4 production, consumption, diffusion, and ebullition under these scenarios. The methods are applied in the second largest reservoir in China (i.e., Danjiangkou Reservoir) as a case study. Results show that annual total sediment CH4 production among the scenarios ranges from 285.9 to 298.3 Gg C year−1, while operation scenario outcomes significantly differ. Specifically, a significant CH4 percentage (34%–39%) is oxidized in surface sediment while the remaining escapes sediment through diffusion and ebullition. Although diffusion accounts for >60% of the annual sediment CH4 release, sediment ebullition ultimately dominates atmospheric CH4 emissions. Annual total atmospheric CH4 emissions range from 42.8 to 71.1 Gg C year−1 and account for 14%–25% of the annual total sediment production among the three scenarios. The differences demonstrate that reservoir operations significantly impact CH4 pathways and atmospheric emissions. This study provides implications for reservoir managers to coordinate socioeconomic and ecological protection while mitigating CH4 emission targets. Key Points: CH4 dynamics are affected by hydrological, hydrodynamic, and water quality factorsEbullient fluxes in shallow‐water and drawdown zones dominate atmospheric emissionOperations impact sediment CH4 consumption, ebullition, and atmospheric emission [ABSTRACT FROM AUTHOR]

Hops are an indispensable ingredient in beer, and the differences in their chemical composition impart the various tastes and aromas associated with different beers. However, during storage, hops undergo changes in their chemical composition. Here, the changes in aroma and bitterness of kettle-hopped beers were evaluated in an experiment conducted on three different hop varieties (Aurora, Celeia and Styrian Wolf) with five different hop storage index (HSI) values (0.3–0.7). Hops were added to boiling wort for 5, 45 and 90 min. Alpha-acids, iso-alpha-acids, humulinones, bitterness units and hop aroma compounds in the samples were chemically analysed. All samples also underwent sensorial analysis. The old hops were not problematic in terms of bitterness or early hopping time. However, later additions of old hops reduced the quality and intensity of the hop aroma. The limit value for use without negative consequences for kettle hopping was set at HSI 0.5 for Aurora and Celeia and HSI 0.6 for Styrian Wolf. [ABSTRACT FROM AUTHOR]

In this study, a novel indirect boiling cooling battery thermal management system with two‐phase coolant R141b is proposed for the commercial cylindrical lithium‐ion battery pack. The heat conduction blocks are used to enlarge the heat transfer area between batteries and straight round tubes, and the R141b coolant flows and boils inside tubes to remove heat generated from batteries. Three‐dimensional simulation models are built and used to study the influence of partial structural parameters (height of heat conduction blocks, number and diameter of round tubes), the flow pattern layout, the coolant flow rate, and the battery discharge rate on the cooling performance of battery thermal management system (BTMS). The results show that the cross‐flow layout significantly improves the temperature uniformity of the batteries, with the maximum temperature difference reduced by 30% compared to the concurrent flow. Meanwhile, the appropriate geometrical parameters can further improve both cooling capacity of the BTMS and the temperature uniformity of the batteries. When the optimized structure with a coolant flow rate of 0.1 L min−1 $\left(\text{L min}\right)^{- 1}$ under the cross‐flow layout, the maximum temperature and maximum temperature difference of batteries discharged at 2 C reduced to 38.6 and 3.81 °C, $°C ,$ which are 97% and 64% of those in the concurrent flow, respectively. [ABSTRACT FROM AUTHOR]

An approach for computing the thermal balance and energy consumption of pits during boiling of frozed logs intended for veneer production has been presented. With the help of our own non-stationary model, the boiling times of beech logs with a diameter of 0.4 m, initial temperature of −10°C, and moisture content of 0.6 kg·kg−1 were determined at water temperatures in the pit equal to 70°C, 80°C and 90°C. Using the determined logs' boiling durations and the mentioned approach, the change in energy required for the entire boiling process and that for each of the components of the thermal balance was calculated. Computer simulations were performed for concrete pit with a volume of 20 m3 and a degree of filling with logs 45%, 60%, and 75%. It was found that the total energy consumption of the pit increases from 169 to 205 kWh·m−3 when the temperature of the boiling water increases from 70°C to 90°C at a pit filling level of 75%. The approach can be applied to compute thermal balances of concrete pits during boiling of frozed and non-frozed logs to any desired final average mass temperature required for the mechanical processing of the plasticized logs. [ABSTRACT FROM AUTHOR]

Methane (CH4) emissions from peat soils are highly variable in space and time and are influenced by changes in biogeochemical controls and other environmental factors. Areas or times with disproportionally high CH4 emissions in wetlands may develop where conditions are especially conducive for microbial processes like methanogenesis. Currently, eddy covariance methods are employed to quantify CH4 exchanges over several extensive subtropical forested wetland communities in the Big Cypress National Preserve, Florida. In this work, we investigate the importance of multi‐scale measurements to characterize CH4 ebullition dynamics from subtropical wetlands. Our approach uses a combination of gas traps, time‐lapse photography, and capacitance probes to characterize ebullition dynamics from two different wetland vegetation communities for comparison to eddy covariance CH4 measurements at the site. Ground‐penetrating radar surveys and soil sampling are used to assess differences in subsurface properties between sites that influence ebullition. Our results show that the mean measurement bias between fluxes measured in this study and the eddy covariance measurements over the same period was 10–14 times larger during the wet season when ebullition rates were greatest, than the dry season, when ebullition rates were smallest. This suggests that eddy covariance measurements may underestimate the CH4 contribution of ebullition across heterogeneous wetland vegetation communities and that the comparability of CH4 fluxes from methods varying in spatio‐temporal scale changes in response to subtropical Florida seasonality. Our work suggests that these methods can be used to complement eddy covariance measurements and improve the characterization of ebullition dynamics in subtropical wetlands. Plain Language Summary: Methane (CH4) gas is emitted from wetlands as a result of a microbial process called methanogenesis. These CH4 gas emissions can be different depending on where and when they are measured because certain wetland areas may have the right conditions to promote methanogenesis more than others. Specialized instruments, called eddy covariance towers, are commonly used to measure CH4 gas emissions. However, because they measure the emissions over a large area, they may not discern smaller scale differences within their measurement area. In contrast, other methods are able to measure CH4 gas emissions at smaller spatial scales, like gas traps, time‐lapse cameras, and capacitance probes. We tested the use of these methods at wetland locations in south Florida where eddy covariance measurements are ongoing. We found consistency between the different scales of measurement but differences from the eddy covariance data were largest during the wet season when CH4 emissions are greatest. Our results are important because they can help identify differences in CH4 gas emission rates for specific wetland environments that can be used in areas where eddy covariance is not available, helping to refine regional and global CH4 emission estimates from wetlands. Key Points: Gas traps coupled with time‐lapse cameras and capacitance probes reveal CH4 ebullition flux heterogeneities between different wetland soilsCombining different scales of measurement allows CH4 ebullition flux heterogeneities to be characterized in subtropical wetlandsComparability of CH4 fluxes from methods varying in spatio‐temporal scale are influenced by subtropical seasonality in ebullition dynamics [ABSTRACT FROM AUTHOR]

The manuscript describes the problem of boiling heat flux determination with the focus on nucleate boiling mode. It presents the boiling phenomenon on the bare surface and provides a review of the correlations that can be used for modelling purposes. Two most commonly applied correlations were validated against the experimental results. One of them showed significant discrepancies, which might be attributed to the conditions of the research and possible variations in the morphology of the heater. The other correlation proved to be successful in determining heat flux. [ABSTRACT FROM AUTHOR]

The Eulerian two‐phase boiling model of the subcooled boiling of coolant in a 3 × 3 fuel assembly is established and compared with the experimental data to verify its accuracy. The effects of four shapes of bow deformation on subcooled boiling flow and heat transfer characteristics are obtained by comparing and analyzing the distributions of thermal–hydraulic parameters, including the axial wall superheat, liquid phase temperature, axial void fraction, various heat fluxes, heat transfer coefficient, and turbulent kinetic energy. All shapes of bow deformation will lead to the redistribution of coolant among different subchannels, and the distributions of thermal–hydraulic parameters would be greatly affected. The bow deformation of fuel rod easily causes local boiling, which results in local high temperature of liquid phase and bubble accumulation, and a decrease in the area of high liquid phase heat transfer coefficient on the surface of bowing fuel rod. Additionally, the non‐uniform distribution of turbulent kinetic energy caused by bow deformation in different axial sections not only affects the heat transfer performance of coolant, but also causes the increment in pressure drop, which has negative effects on the safe operation of the nuclear reactor. This paper can provide data and theoretical support for engineering design. [ABSTRACT FROM AUTHOR]

Boiling heat transfer on nanostructured surfaces presents great potential in cooling highly integrated microelectronic devices. Analysis of the factors affecting boiling heat transfer included the analysis of nanostructure and wettability, indicating that consideration of the influence of working liquid quantity is essential in finite spaces. Rapid boiling water films with various thicknesses placed on the same nanochannel copper plate were studied via molecular dynamics (MD) simulations. The simulation results reveal that the potential energy difference in the vapor–liquid coexisting region on the nanochannels was lower for thicker films, and the evaporation rate was lower. The effect of water film thickness on boiling heat transfer is closely related to the potential energy difference in the vapor–liquid coexisting region on the nanochannels. The heat transfer effect was the worst in case 1, where the water thickness was lower than the height of the nanochannels. This is because there is no guaranteed liquid replenishment at the nucleation points, although the potential energy difference was greatest in the vapor–liquid coexistence zone of case 1. Evaporation was the greatest in case 2, where the water film just covered the nanochannels because of the larger potential energy difference and sufficient liquid water replenishment. This study is of great significance for the analysis of the vapor–liquid flow mechanisms of micro/nanostructured surfaces and the improved design of thermal management equipment of micro/nano devices. [ABSTRACT FROM AUTHOR]

Microchannel flow boiling is an efficient cooling method for high-heat-flux electronic devices. To understand the flow boiling regime in a T-shaped microchannel, this paper prepared T-shaped microchannels of different sizes and designed an experimental platform for the visualization of flow boiling in microchannels, and aimed to study the evolution characteristics of two-phase flow patterns in T-shaped microchannels. The influences of the flow rate and channel size on the boiling flow pattern inside a T-shaped microchannel were experimentally observed and quantitatively described. The results indicate that the occurrence position of the vaporization core gradually migrates from branch channel to main channel as the wall temperature increases. The flow boiling at the bifurcation of the T-shaped microchannel mainly includes the extrusion fracture flow, bubble flow, plug–annular alternating flow and annular flow, in which the annular flow can be further divided into the intermittent annular flow and the stable annular flow. In addition, a high flow rate and small channel size can lead to the disappearance of the bubble flow, and the presence of the bubble flow delays the appearance of the annular flow. [ABSTRACT FROM AUTHOR]

Background: Storage reservoirs of radioactive waste could be the source of atmospheric pollution due to the efflux of aqueous aerosol from their water areas. The main mechanism of formation of aqueous aerosols is the collapse of gas bubbles at the water surface. In this paper, we discuss the potential influence of biological factors on gas ebullition in the water areas of the radioactively contaminated industrial reservoirs R-9 (Lake Karachay) and R-4 (Metlinsky pond) of the Mayak PA. The emission of the released non-dissolved gases captured with gas traps in reservoir R-9 was (88–290) ml/m2 per day (2015) and in reservoir R-4 (270–460) ml/m2 per day (2016). The analysis of gas composition in reservoir R-4 (60% methane, 35% nitrogen, 2.4% oxygen, 1.5% carbon dioxide) confirms their biological origin. It is associated with the processes of organic matter destruction in bottom sediments. The major source of organic matter in bottom sediments is the dying phytoplankton developing in these reservoirs. Conclusion: The obtained results form the basis to set a task to quantify the relationship between the phytoplankton development, gases ebullition and radioactive atmosphere contamination.

Electronically excited NdO is a possible product of the chemistry associated with the release of Nd into the ionosphere, and emission from these states may contribute to the observations following such experiments. To better characterize the energetics and spectroscopy of NdO, we report a combined experimental and theoretical study using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled NdO− anions (cryo-SEVI) supplemented by wave function-based quantum-chemical calculations. Using cryo-SEVI, we measure the electron affinity of NdO to be 1.0091(7) eV and resolve numerous transitions to low-lying electronic and vibrational states of NdO that are assigned with the aid of the electronic structure calculations. Additionally, temperature-dependent data suggest contributions from the (2)4.5 state of NdO− residing 2350 cm−1 above the ground anion state. Photodetachment to higher-lying excited states of NdO is also reported, which may help to clarify observations from prior release experiments. [ABSTRACT FROM AUTHOR]

Electronically excited NdO is a possible product of the chemistry associated with the release of Nd into the ionosphere, and emission from these states may contribute to the observations following such experiments. To better characterize the energetics and spectroscopy of NdO, we report a combined experimental and theoretical study using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled NdO− anions (cryo-SEVI) supplemented by wave function-based quantum-chemical calculations. Using cryo-SEVI, we measure the electron affinity of NdO to be 1.0091(7) eV and resolve numerous transitions to low-lying electronic and vibrational states of NdO that are assigned with the aid of the electronic structure calculations. Additionally, temperature-dependent data suggest contributions from the (2)4.5 state of NdO− residing 2350 cm−1 above the ground anion state. Photodetachment to higher-lying excited states of NdO is also reported, which may help to clarify observations from prior release experiments. [ABSTRACT FROM AUTHOR]